﻿using System;

class Circle
{
    private double radius;
    public Circle(double radius)
    {
        this.radius = radius;
    }

    public double CalculateCircumference()
    {
        return 2 * Math.PI * radius;
    }

    public double CalculateArea()
    {
        return Math.PI * radius * radius;
    }
}

class Program
{
    static void Main(string[] args)
    {
        Circle circle = new Circle(5);
        double circumference = circle.CalculateCircumference();
        Console.WriteLine("圆的周长为：" + circumference);
        double area = circle.CalculateArea();
        Console.WriteLine("圆的面积为：" + area);
    }
}
